Laser depilating method and laser depilating apparatus

ABSTRACT

A laser depilating method for depilating treatment by irradiating a skin surface with a laser beam emitted from a semiconductor laser. A treatment region of the skin surface is treated with a semiconductor laser beam for an irradiation time of 100 msec or more per irradiation while controlling the laser beam so that the energy density when irradiating the skin surface may be in a range of 0.01-1 J/mm 2 . Irradiation of the skin surface with a semiconductor laser beam under such a condition provides a more secure and efficient treatment effect of laser depilation. A plurality of semiconductor laser beams are used as necessary to irradiate a wider area of skin surface at a time.

TECHNICAL FIELD

[0001] The present invention relates to a laser depilating method and alaser depilating apparatus for depilating treatment with a laser beamfrom a semiconductor laser.

BACKGROUND ART

[0002] A conventional body hair depilating treatment (treatment forretarding or lowering the regrowth of hair) was performed by burning outhair roots by an electrical needle. This treating method must treat hairone by one, taking a very long treating time and causing pain duringtreatment. Therefore, a laser depilating treatment is now being usedinstead of the depilating treatment using the electrical needle.

[0003] The laser depilating treatment is a treatment which retards theregrowth (growth) of hair by giving thermal or physical damage to agerminative cell and hair papilla of a hair bulb at the hair root andalso to a bulge and a sebaceous gland with a laser beam. For theconventional laser depilating treatment, various types of laserirradiation devices such as a YAG laser (oscillation wavelength:approximately 1064 nm), a ruby laser (oscillation wavelength:approximately 694 nm), an alexandrite laser (oscillation wavelength:approximately 755 nm) and a semiconductor laser (oscillation wavelength:approximately 800 nm) as described in, for example, Japanese NationalStage Laid-Open Publication No. 2001-500529 (International PublicationNo. WO98/48716) are used.

[0004] Among them, a depilating treatment apparatus using the YAG laseror the ruby laser is an apparatus which irradiates a skin surface with ahigh power laser beam to directly destroy (e.g., thermolysis) a hairroot, a germinative cell and the like. A laser beam of the YAG laser orthe like has a long wavelength and poor absorption efficiency by melaninin a hair root and germinative cell, and its power is high, so that itsirradiation time per irradiation is limited. Besides, the depilatingtreatment apparatus using the YAG laser utilizes a very expensivemedical laser irradiation device, and the depilating treatment must beperformed as medical treatment.

[0005] Meanwhile, a laser depilating apparatus using a small andinexpensive semiconductor laser (laser diode) has a low power (e.g.,approximately 0.01 to 10W) laser beam emitted from the semiconductorlaser, so that the laser depilating treatment can be performed ascosmetic treatment. The semiconductor laser beam has a wavelength of,for example, approximately 780 to 810 nm. This laser beam having such awavelength is hardly absorbed by water or blood but has very highabsorption efficiency by melanin in a hair root (hair shaft) and agerminative cell. Thus, the regrowth (growth) of hair can be retardedefficiently by thermal energy of the laser beam absorbed by the melanin.

[0006] As described above, the laser depilating apparatus using thesemiconductor laser has a feature that the semiconductor laser beam hasa wavelength suitable for the depilating treatment. However, theconventional laser depilating apparatus does not have an irradiationtime, irradiation energy and other various kinds of conditions forirradiation of the semiconductor laser beam examined adequately ordecided, so that an adequate depilating effect cannot be obtaineddepending on the situation or hair is reversely grown.

[0007] For example, Japanese Patent Unexamined Publication No.2000-201726 describes a laser depilating apparatus which is comprised ofa semiconductor laser having light power of 5 to 1000 mW, light poweradjusting means for adjusting the light power of the laser beam emittedfrom the semiconductor laser, and irradiation time setting means forsetting an irradiation time of the laser beam. Here, the light power ofthe laser beam is adjusted by the on-time of the laser pulse, so thatthermal energy based on the irradiation of the laser beam might not beconducted effectively to the entire hair follicle tissue. Besides, thereis no suggestion about an energy density or the like of the laser beameffective for the depilating treatment.

[0008] Japanese Patent Unexamined Publication No. 2001-46141 describes alaser depilating apparatus which is comprised of a laser diode forirradiating a laser beam, a control section for controlling anirradiation time of the laser beam and an output control circuit foradjusting a voltage or a current applied to the laser diode. But, theabove publication does not describe specific power of the laser beam(semiconductor laser beam), an irradiation time or an energy density ofthe laser beam effective for depilating treatment.

[0009] Japanese Patent Unexamined Publication No. 2000-245525 describeslaser therapy equipment using an alexandrite laser (oscillationwavelength: approximately 755 nm) having a wavelength similar to that ofthe semiconductor laser. Here, it is shown that the laser beam power isgenerally in a range of 10 to 40 J/cm² (0.1 to 0.4 J/mm²). However, thealexandrite laser has the same high power as the YAG laser does, so thatits laser irradiation time is limited to 10 to 40 msec. Besides, thehigh power alexandrite laser directly destroys (cauterizes) a hair rootand the like in the same way as the YAG laser to perform the depilatingtreatment, so that the depilating treatment cannot be performed byconducting the thermal energy of the laser beam to the entire hairfollicle tissue like the semiconductor laser.

[0010] In addition, the conventional laser depilating apparatus isdifficult to increase an irradiated area per treatment with the laserbeam while keeping the energy density effective for depilating. JapanesePatent Unexamined Publication No. 2000-217938 describes a laserdepilating apparatus having a plurality of semiconductor lasers (laserdiodes) which are circularly disposed. By using the plurality ofsemiconductor lasers, an irradiation area of the laser beam isincreased. But, the plurality of semiconductor lasers circularlydisposed are limited from increasing the irradiation area of the laserbeam, and if the irradiation area is excessively increased, the laserbeam might have a nonuniform energy density.

[0011] Therefore, it is desired to increase an irradiation area of thesemiconductor laser beam so to improve the depilating effect of thesemiconductor laser beam. There is some consideration being made ondisposition of many laser diode elements in an array shape to use asemiconductor laser having high power equivalent to that of the YAGlaser. But, such a laser irradiation device has variations in powerdensity because the laser beams emitted from the individual diodeelements cause interference with each other. And, because thesemiconductor laser beam is designed to have high power, the feature ofthe semiconductor laser beam that the absorption efficiency by melaninis high cannot be utilized fully.

[0012] The present invention is to provide a laser depilating method andlaser depilating apparatus which can provide a laser depilating effectmore securely and efficiently by utilizing the feature of thesemiconductor laser beam that the absorption efficiency by melanin inhair shafts and germinative cells is high. Besides, it also provides alaser depilating apparatus having a treatment region increased and atreatment speed improved while keeping the depilating effect of thesemiconductor laser beam.

DISCLOSURE OF THE INVENTION

[0013] The laser depilating method of the present invention is a laserdepilating method for depilating treatment by irradiating a skin surfacewith a laser beam emitted from a semiconductor laser, comprisingirradiating a treatment region of the skin surface with the laser beamfor an irradiation time of 100 msec or more per irradiation whilecontrolling an energy density to a range of 0.01 to 1 J/mm² when theskin surface is irradiated with the laser beam; and performing thedepilating treatment by transmitting thermal energy based on theirradiation of the laser beam to the entire hair follicle tissue of thetreatment region. In the laser depilating method of the invention, thelaser beam (a semiconductor laser beam) emitted from the semiconductorlaser has a wavelength in a range of, for example, 750 to 900 nm.

[0014] The laser depilating apparatus of the invention is a laserdepilating apparatus, comprising a semiconductor laser for emitting alaser beam having a wavelength in a range of 750 to 900 nm; a radiatinghead having a light path for guiding the laser beam and a laserirradiation surface so to irradiate a skin surface subject to depilatingtreatment with the laser beam emitted from the semiconductor laser; anirradiation condition control section for controlling an energy densityto a range of 0.01 to 1 J/mm² when the skin surface is irradiated withthe laser beam while keeping the irradiation time of the laser beam at100 msec or more per irradiation.

[0015] According to the present invention, the irradiation time perirradiation (one time) of the semiconductor laser beam having theabove-described wavelength is controlled to 100 msec or more. Thus, itbecomes possible to effectively and efficiently use the thermal energyof the semiconductor laser beam. In other words, when the irradiationtime of the semiconductor laser beam is set to 100 msec or more, thethermal energy of the semiconductor laser beam absorbed by melanin inthe hair shafts and germinative cells can be conducted to the entirehair follicle tissue (hair bulb, hair shaft, and connective tissueincluding sheath, bulge, sebaceous gland and the like around the hairshaft). The thermal damage is securely and efficiently applied to theentire hair follicle tissue to exert an influence on the regrowth ofhair, so that the regrowth of hair can be retarded without fail.

[0016] Even if the irradiation time per irradiation of the semiconductorlaser beam is simply extended, the thermal energy becomes insufficientand the thermal damage cannot be applied efficiently to the entire hairfollicle tissue if an energy density is insufficient when thesemiconductor laser beam is irradiated to a skin surface. Therefore, toobtain the hair regrowth retarding effect with reliability, the energydensity of the semiconductor laser beam is controlled to a range of 0.01to 1 J/mm². By using the semiconductor laser beam having the aboveenergy density, the thermal energy having a high depilating effect canbe conveyed securely and efficiently to the entire hair follicle tissue.

[0017] The laser depilating apparatus of the invention is furthercomprised of the semiconductor laser in plural numbers; and an opticalsystem for gathering a plurality of laser beams emitted from theplurality of semiconductor lasers and forming so that the entire regionof the laser irradiation surface of the radiation head is substantiallyirradiated with the laser beams. The radiating head has, for example, arectangular laser irradiation surface, and the plurality ofsemiconductor lasers are disposed so that the plurality of laser beamsirradiate substantially different regions in the rectangular laserirradiation surface.

[0018] By the laser depilating apparatus provided with the plurality ofsemiconductor lasers, the semiconductor laser beams having asubstantially constant power density can be collectively irradiated to awide rang of skin surface. The depilating treatment can be performed ona wide range by a single laser irradiation by increasing an irradiationrange (irradiation area) of the semiconductor laser beam. Therefore, atreating speed can be increased substantially without degrading thedepilating effect by the semiconductor laser beam.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a perspective view schematically showing a generalstructure of the laser depilating apparatus according to an embodimentof the present invention.

[0020]FIG. 2 is a front view showing a laser radiating probe of thelaser depilating apparatus of FIG. 1.

[0021]FIG. 3 is a vertical sectional view taken along line A-A of thelaser radiating probe shown in FIG. 2.

[0022]FIG. 4 is a transverse sectional view taken along line B-B of thelaser radiating probe shown in FIG. 2.

[0023]FIG. 5 is a view showing an irradiating state of a plurality ofsemiconductor laser beams in a laser irradiation surface of the laserradiating probe shown in FIG. 2.

[0024]FIG. 6 is a block view showing a structure of a drive controlsection of a semiconductor laser of the laser depilating apparatus shownin FIG. 1.

[0025]FIG. 7 is a view illustrating an irradiation time of asemiconductor laser beam according to one embodiment of the presentinvention.

[0026]FIG. 8 is a view illustrating a state of body hair which is atarget of laser depilating treatment.

[0027]FIG. 9 is a block diagram showing a structure of a drive controlsection of a semiconductor laser of the laser depilating apparatusaccording to another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] Modes for practicing the present invention will be described.

[0029]FIG. 1 is a perspective view schematically showing a generalstructure of the laser depilating apparatus according to an embodimentof the present invention. In the drawing, 1 is a laser depilatingapparatus body having an operation panel 2, and the apparatus body 1 hastherein a main power supply, a semiconductor laser power supply, acontrol circuit for controlling the drive of a semiconductor laser, theoperation of a compressor and the like, a circuit for a confirmationscreen, and the like.

[0030] A laser radiating probe 4 is connected to the laser depilatingapparatus body 1 through a cable 3. The laser radiating probe 4 isconfigured to be freely movable by an angle adjusting arm 5. The cable 3contains therein lead wires for connecting the semiconductor laser powersupply of the apparatus body 1 and between the control circuit and thelaser radiating probe 4, an air tube for supplying air from thecompressor to the laser radiating probe 4, and the like.

[0031] The laser depilating apparatus body 1 has a CCD camera-mountedconfirmation probe which is not shown. Laser depilating treatment can beperformed while checking a skin surface with an image taken by the CCDcamera of the confirmation probe. The image taken by the CCD camera isshown on a color liquid crystal screen 6 of the operation panel 2. Onthe operation panel 2, a touch-sensitive operation screen 7, a mainpower switch (not shown) and the like are disposed.

[0032]FIG. 2, FIG. 3 and FIG. 4 are views showing a structure of thelaser radiating probe 4. FIG. 2 is a front view of the laser radiatingprobe 4, FIG. 3 is a vertical sectional view taken along line A-A ofFIG. 2, and FIG. 4 is a transverse sectional view taken along line B-Bof FIG. 2. As shown in these drawings, a plurality of semiconductorlasers 8, 8 . . . are disposed as a laser source within the laserradiating probe 4. The number of semiconductor lasers 8 is not limitedto be multiple, but a single semiconductor laser can be used toconfigure the laser depilating apparatus. When the plurality ofsemiconductor lasers 8 are used, the semiconductor lasers 8 are used inthe number of, for example, 2 to 50. The laser depilating apparatus ofthis embodiment has 20 semiconductor lasers 8 as described later.

[0033] For the semiconductor lasers 8, laser diodes which emit laserbeams having a wavelength in a range of, for example, 750 to 900 nm areused. The laser beams having a wavelength in a range of 750 to 900 nmprovide favorable depilating effects because, for example, theyrelatively deeply penetrate the skin of a human body and are absorbed bymelanin in a hair shaft and germinative cell with priority as comparedwith water or blood (hemoglobin). In other words, a laser beam having awavelength of less than 750 nm is absorbed at a high rate by melanin butalso absorbed substantially by blood or the like, possibly loweringutilization efficiency of a laser beam for depilating treatment anddamaging the skin and the like. Meanwhile, when a laser beam has awavelength of exceeding 900 nm, the absorption factor by melanin lowers,and a favorable depilating effect cannot be obtained. It is particularlydesirable that the semiconductor laser beam has a wavelength in a rangeof 780 to 810 nm (800 nm as median).

[0034] The semiconductor laser 8 preferably has a power of 0.1W or more.A semiconductor laser having a power of less than 0.1W can be used, butthe laser beam might not penetrate the skin sufficiently, thoughvariable depending on the wavelength of such a low power semiconductorlaser. Such a laser beam does not adequately reach the hair bulb and thelike, so that a favorable depilating effect cannot be obtained, and hairmight be restored depending on circumstances. The semiconductor laser 8preferably has a power of 0.5W or more, and more preferably 1W or more,in order to penetrate the laser beam effectively into the skin.

[0035] But, if the semiconductor laser has an excessively high power, itis necessary to reduce an irradiation time of the laser beam, thoughvariable depending on a spot size. Therefore, the thermal energy by thesemiconductor laser beam might not be distributed over the entire hairfollicle tissue. Therefore, the semiconductor laser 8 preferably has apower of 50W or less. Thus, the present invention desirably uses thesemiconductor laser 8 having a power in a range of 0.1 to 50W. Thesemiconductor laser 8 has more preferably a power in a range of 0.5 to10W, and still more preferably in a range of 1 to 10W.

[0036] The spot size (laser radiation area of one semiconductor laser 8)of each semiconductor laser 8 is ideally about 2 to 4 times of apenetration depth of the laser beam. It is necessary to consider thepower of the semiconductor laser 8, but it is desirable in practice thatan irradiation area of a laser beam by the semiconductor laser 8 is setto a range of 0.5 to 20 mm². The spot size (laser radiation area) ofeach semiconductor laser 8 is desirably set to a range of 0.5 to 10 mm²,and more desirably in a range of 0.7 to 8 mm².

[0037] The plurality of semiconductor lasers 8, 8 . . . are held by aholding member 9 having a substantially spherical laser holding surface.Lenses (e.g., spherical lenses) 10, 10 . . . are respectively disposedin front of radiation by the plurality of semiconductor lasers 8, 8 . .. . The laser beams emitted by the individual semiconductor lasers 8 arefocused on a radiating head 11 through the individual lenses 10. Theradiating head 11 is made of, for example, quartz glass and makes asubstantial contact with a skin surface which is subject to the laserdepilating treatment.

[0038] The radiating head 11 has a light path therein to guide theindividual semiconductor laser beams to a prescribed treatment region ofa skin surface. The front face of the radiating head 11 is a laserirradiation surface 12. The individual laser beams emitted from theplurality of semiconductor lasers 8, 8 . . . are focused into theradiating head 11 by the lenses 10, 10 . . . . The individualsemiconductor laser beams are determined to have light paths so to passthrough prescribed portions in the radiating head 11 and shaped to havea spot size suitable for the laser depilation within the radiating head11. The individual light paths in the radiating head 11 are set toradiate a substantially entire region of the laser irradiation surface12 with the semiconductor laser beams. Therefore, the plurality ofsemiconductor laser beams are radiated to a skin surface correspondingto the area of the laser irradiation surface 12.

[0039] A relationship between the state of holding the plurality ofsemiconductor lasers 8, 8 . . . and the irradiation region of theplurality of semiconductor laser beams will be described in furtherdetail. The laser depilating apparatus of this embodiment has, forexample, 20 semiconductor lasers 8, 8 . . . . These 20 semiconductorlasers 8, 8 . . . are basically disposed in the shape of a matrix with 5rows and 4 columns.

[0040] The holding member 9 for holding these 20 semiconductor lasers 8,8 . . . has a laser holding surface which is spherical in the verticalsectional direction in FIG. 3 and circumflex in the transverse sectionaldirection in FIG. 4. The 20 semiconductor lasers 8, 8 . . . are set bythe holding member 9 to have optical axes so that rays of light aregathered into the radiating head 11. The 20 semiconductor lasers 8, 8 .. . are held by the holding member 9 having the above-described laserholding surface in such a way that a distance from the each lightemitting point to the light-gathering point in the radiating head 11becomes substantially constant.

[0041] Meanwhile, the radiating head 11 has a rectangular laserirradiation surface 12. The laser irradiation surface 12 has a shape of,for example, 15×12 mm. In other words, the radiating head 11 has a laserradiation area of 15×12 mm (area=180 mm²). The area of the laserirradiation surface 12 can be set appropriately according to thedisposed number of semiconductor lasers 8, the contents of treatment andthe like. When one semiconductor laser is used, its spot size becomes alaser radiation area. When a plurality of semiconductor lasers are used,the laser irradiation surface 12 preferably has an area of 15 mm² ormore, and more preferably 50 mm² or more.

[0042] The semiconductor laser beams emitted from the individualsemiconductor lasers 8 are formed to have prescribed spot sizesaccording to gathering of light according to the individual lenses 10,refraction at the time of incidence to the radiating head 11 and alength of light path by the radiating head 11. Besides, the individualsemiconductor laser beams are set to have light paths so to pass throughprescribed portions in the radiating head 11 depending on the shape ofthe holding member 9, the state of holding the semiconductor lasers 8 bythe holding member 9, a positional relationship between thesemiconductor lasers 8 and the radiating head 11, and the like. Theindividual light paths are determined in such a way that thesemiconductor laser beams respectively irradiate substantially differentregions in the laser irradiation surface 12, and the entire region ofthe laser irradiation surface 12 is substantially irradiated with thesemiconductor laser beams.

[0043] As shown in FIG. 5, a plurality of semiconductor laser beams X, X. . . are configured to have light paths so to irradiate substantiallydifferent regions in the laser irradiation surface 12. The irradiationpositions in the laser irradiation surface 12 by the plurality ofsemiconductor laser beams X, X . . . are in a matrix with 5 rows and 4columns according to the number of semiconductor lasers 8 so to cover asubstantially entire region of the laser irradiation surface 12. And,the rectangular laser irradiation surface 12 is substantially irradiatedits entire region with the plurality of semiconductor laser beams X, X .. . .

[0044] The state of irradiation of the substantially different regionsin the laser irradiation surface 12 with the plurality of semiconductorlaser beams X, X . . . is adequate when the individual semiconductorlaser beams X have at least different irradiation centers, and theneighboring semiconductor laser beams X may have somewhat overlappedirradiation ranges. The state that the entire region of the laserirradiation surface 12 is substantially irradiated with the plurality ofsemiconductor laser beams X, X . . . may be a state that it provides adepilating effect on the entire skin surface equivalent to the area ofthe laser irradiation surface 12 with the semiconductor laser beams X.There may be a small gap formed between the irradiation ranges of theneighboring semiconductor laser beams X, and even in such a case, thedepilating effect can be provided by irradiation heat of thesemiconductor laser beams X.

[0045] The plurality of semiconductor laser beams X, X . . . each have asubstantially constant power density. Therefore, the laser beams havinga substantially constant power density are collectively irradiated tothe laser irradiation surface 12 of the radiating head 11. A skinsurface is irradiated with the semiconductor laser beams X depending onthe area of the rectangular laser irradiation surface 12, so that thelaser beams having a substantially constant power density arecollectively irradiated into the treatment region of the skin surface.The laser irradiation surface 12 (irradiation area: 180 mm²) of thelaser depilating apparatus of this embodiment has a shape of, forexample, 15×12 mm. Therefore, a skin surface having substantially thesame area can be irradiated with the semiconductor laser beams Xcollectively. By the laser depilating apparatus of this embodiment, itis possible to expand the region of depilating treatment per laserirradiation according to the irradiation state with the plurality ofsemiconductor laser beams X, X . . . .

[0046] A plurality of cooling air nozzles 13 are formed around theradiating head 11 of the laser radiating probe 4. Cooling air issupplied before, simultaneously with or after irradiation with thesemiconductor laser beams. The temperature of the skin also risesslightly when the skin surface is irradiated with the semiconductorlaser beams, but damage to the skin can be retarded more securely byblowing cooling air to the skin surface when irradiated with thesemiconductor laser beams. Cooling gel or the like may also be used whenirradiated with the semiconductor laser beams.

[0047] In the laser depilating apparatus of the above embodiment, a skinsurface is irradiated with the semiconductor laser beams for anirradiation time of 100 msec or more per one time of irradiation whilecontrolling an energy density to a range of 0.01 to 1 J/mm² when theskin surface of a human body subject to the depilating treatment isirradiated. When the skin surface is irradiated with the semiconductorlaser beams, an energy density E is controlled by at least one of anirradiation time T and a power density L of the semiconductor laserbeams. The above irradiation conditions of the semiconductor laser beamssatisfy a relationship of an energy density E [J/mm²]=power density L[W/mm²]×irradiation time T [sec]. Therefore, the energy density iscontrolled to a desired range by adjusting the irradiation time T and/orthe power density L of the semiconductor laser beams.

[0048] In practice, the power density L of the laser beams by thesemiconductor lasers 8 is preferably determined to fall in a range of0.01 to 5W/mm² depending on the irradiation time T. If the power densityL of the semiconductor laser beams in the irradiation region is lessthan 0.01 W/mm², an adequate depilating effect might not be obtainedeven if the irradiation time per irradiation of the semiconductor lasers8 is extended. Meanwhile, when the semiconductor laser beams have apower density L of exceeding 5 W/mm², the irradiation time per one timecannot be determined to be long enough, and the thermal energy might notbe distributed to cover the entire hair follicle tissue. It is desirablethat the power density L of the semiconductor laser beams is set to arange of 0.05 to 2 W/mm².

[0049] The power density L of the semiconductor laser beams isdetermined according to power C of the semiconductor lasers 8 and spotsize S of the semiconductor laser beams. In other words, it meets therelationship of power density L [W/mm²]=power C [W]/spot size S [mm²].The spot size S is basically determined to be constant, so that thepower density L of the semiconductor laser beams is controlled accordingto the power C of the semiconductor lasers 8. The output (light output)C of the semiconductor lasers 8 is controlled by a voltage value orcurrent value input to the semiconductor laser (laser diode) 8.

[0050] The light output of the semiconductor laser beams can also becontrolled by, for example, varying the on-time of the laser pulse withthe semiconductor lasers 8 as pulse oscillation. But, the pulsedsemiconductor laser beam cannot convey the thermal energy to the entirehair follicle tissue efficiently. The semiconductor lasers 8 are desiredto be continuously oscillated in order to enhance the transmissionefficiency of the thermal energy. Therefore, the light output of thesemiconductor lasers 8 is controlled by the voltage value or currentvalue input to the semiconductor lasers 8.

[0051]FIG. 6 is a block view showing a structure of the drive controlsection of the semiconductor lasers 8. A control section 101 readscontrol signals for the drive conditions (voltage or current value) anddrive time (laser beam irradiation time) of the semiconductor lasers 8from a storage section 103 according to a treatment mode or the likeinput from an operation section 102. Among the control signals read fromthe storage section 103, the drive condition signal for thesemiconductor lasers 8 is sent from the control section 101 to a laserdrive circuit 105 via a D/A conversion circuit 104. The drive timesignal for the semiconductor lasers 8 is sent from the control section101 to the laser drive circuit 105.

[0052] According to the control signal, the laser drive circuit 105inputs a prescribed voltage value or current value from an unshown laserdrive power supply to the semiconductor lasers 8. Time of applying aninput current is controlled by the laser drive circuit 105 according tothe control signal. Thus, the power C and drive time (a laser beamirradiation time T) of the semiconductor lasers 8 are controlled. Thespot size S of the semiconductor laser beams is basically determined tobe constant, so that the power density L of the semiconductor laserbeams is controlled by the power C of the semiconductor lasers 8.

[0053] The drive time (laser beam irradiation time T) of thesemiconductor lasers 8 is set to 100 msec or more. After meeting theabove condition, energy density E at the irradiation of a skin surfacewith the semiconductor laser beams is controlled according to the powerdensity L and the irradiation time T of the semiconductor laser beams.The irradiation energy density E of the semiconductor laser beams isspecifically controlled to a range of 0.01 to 1 J/mm². And, a skinsurface is irradiated with the semiconductor laser beams having theabove irradiation time T and irradiation energy density E to perform thedepilating treatment by conveying the thermal energy based on theirradiation of the semiconductor laser beams to the entire hair follicletissue.

[0054] It is important that a treatment region of the skin surface isirradiated with the semiconductor laser beams for an irradiation time of100 msec or more per irradiation. Here, the irradiation time perirradiation of the semiconductor laser beam is a lighting time (ON-time)T per treatment by the semiconductor laser 8 as shown in FIG. 7. Thesemiconductor lasers 8 are basically driven by continuously oscillating,so that the irradiation time per irradiation of the semiconductor laserbeam corresponds to the irradiation time per treatment.

[0055] As described above, the thermal energy of the laser beamsabsorbed by melanin in the hair shaft and germinative cell can beconducted to the entire hair follicle tissue by irradiating a skinsurface with the semiconductor laser beams determined to have theirradiation time T of 100 msec or more per irradiation. Specifically,when a skin surface 21 is irradiated with the semiconductor laser beamsX with the irradiation time T set to 100 msec or more per irradiation asshown in FIG. 8, the semiconductor laser beams X penetrate the skin andare selectively absorbed by melanin contained in a hair shaft 22 and agerminative cell 24 of a hair bulb 23. The hair shaft 22 and thegerminative cell 24 having selectively absorbed the semiconductor laserbeams X are heated to a prescribed temperature of, for example, about 60to 100° C. by the thermal energy of the semiconductor laser beams X.

[0056] At this time, the irradiation time T of the semiconductor laserbeams X per irradiation is set long to be 100 msec or more. Therefore,the thermal energy absorbed by the melanin in the hair shaft 22 and thegerminative cell 24 is sufficiently propagated to their peripheries.Accordingly, the hair shaft 22, the germinative cell 24 and a hairpapilla 25, and the entire hair follicle tissue including a sheath 26 asconnective tissue around them, a stem tissue 27, a sebaceous gland 28and a bulge 29 can be heated securely and efficiently to a temperatureeffective for depilating. A region having a temperature of approximately60 to 100° C. which is considered to be effective for depilating isapproximately equal to or larger than a diameter of the hair follicle,and thermal damage is applied to a region having such a temperature.

[0057] As described above, when the semiconductor laser beam X isdetermined to have the irradiation time T of 100 msec or more perirradiation, the thermal damage can be given effectively and securely tothe entire hair follicle tissue. And, the regrowth of hair can beretarded surely by applying thermal damage to the entire hair follicletissue, namely not only the hair shaft 22 and the germinative cell 24but also the sheath 26 as the connective tissue and the stem tissue 27,the sebaceous gland 28 and the bulge 29 with the semiconductor laserbeams X. In other words, the depilating effects based on the hair growthretarding effect and the reducing effect can be obtained securely andefficiently. In addition, the depilating treatment can be performedsafely because the skin can be prevented from having a high temperature.

[0058] Meanwhile, when the semiconductor laser beam has an irradiationtime T of less than 100 msec per irradiation, the thermal energy is notconducted sufficiently by the semiconductor laser beams having the samepower density as above, and thermal damage cannot be given adequately tothe entire hair follicle tissue. When the power density of thesemiconductor laser beams is increased to a level capable of attainingthe depilating effects, the hair shaft 22 and the germinative cell 24are excessively heated to cause a thermally insulated state and sufferfrom decomposition and vaporization. It means that the absorber for thesemiconductor laser beams is lost, and a temperature is caused to dropby the heat of vaporization. Thus, the thermal damage cannot be giveneffectively to the entire hair follicle tissue. Besides, the skintemperature might become high, and a side effect might be caused as aresult.

[0059] The irradiation time T per irradiation of the semiconductor laserbeams can be set appropriately to a range of retarding the skin fromhaving a high temperature or damage resulting from it but preferably setto 10 sec or less in view of practical use. The irradiation time T perirradiation of the semiconductor laser beams is preferably set to 100msec or more and 10 sec or less. Besides, the irradiation time T perirradiation of the semiconductor laser beams X is particularly desiredto be in a range of 1 to 5 sec considering the laser depilating effectand safety.

[0060] Not only the irradiation time T per irradiation of thesemiconductor laser beam but also the energy density E of thesemiconductor laser beam are pertinent to the laser depilating effect.Specifically, even if the irradiation time T per irradiation of thesemiconductor laser beam is set to be long, the thermal damage cannot begiven efficiently to the entire hair follicle tissue when the energydensity E of the semiconductor laser beam is excessively low. Therefore,the energy density E of the semiconductor laser beam is controlled to arange of 0.01 to 1 J/mm² while keeping the irradiation time T perirradiation of the semiconductor laser beam to 100 msec or more.

[0061] As described above, the energy density E and the irradiation timeT satisfy the relationship of the energy density E [J/mm²]=power densityL [W/mm²]×irradiation time T [sec]. Therefore, the energy density E ofthe semiconductor laser beams is controlled to a range of 0.01 to 1J/mm² by adjusting the irradiation time T and the power density L of thesemiconductor laser beams while the irradiation time T per irradiationof the semiconductor laser beam is kept to 100 msec or more. When thesemiconductor laser beams having the energy density E are used, it ispossible to conduct the thermal energy having a high depilating effectto the entire hair follicle tissue securely and efficiently.

[0062] When the energy density E of the semiconductor laser beams isless than 0.01 J/mm², the thermal damage cannot be given to the entirehair follicle tissue. Meanwhile, when the energy density E exceeds 1J/mm², the hair shafts and germinative cells might be decomposed, theskin might have a high temperature, and a side effect might be caused asa result. The energy density E of the semiconductor laser beam isespecially desired to be controlled to a range of 0.1 to 0.4 J/mm². Thisirradiation energy density E can give thermal damage to the hairfollicle tissue more effectively.

[0063] As described above, the thermal damage can be caused effectivelyand securely to the entire hair follicle tissue with the semiconductorlaser beam which is set to have the irradiation time T of 100 msec ormore per irradiation and the irradiation energy density E controlled toa range of 0.01 to 1 J/mm². Thus, an effect of retarding the growth ofhair and an effect of lowering it can be obtained securely andefficiently. Specifically, it becomes possible to obtain the laserdepilating effects securely and efficiently by making use of a featureof the semiconductor laser beam that the absorption efficiency bymelanin in hair shafts and germinative cells is high. In addition, thedepilating treatment can be performed safely because the skintemperature does not become high.

[0064] Besides, the laser depilating apparatus of this embodiment emitsthe laser beams having a substantially constant power density from thelaser irradiation surface 12 of the radiating head 11 by gathering theplurality of laser beams emitted from the plurality of semiconductorlasers 8, 8 . . . and forming. An irradiation range (irradiation area)of the semiconductor laser beams having the substantially constant powerdensity is substantially expanded, so that the depilating treatment canbe performed on a large region by a single laser irradiation. Therefore,it is possible to enhance a depilating treatment speed extensivelywithout lowering the depilating effects by the semiconductor laserbeams.

[0065] Especially, the laser depilating apparatus of this embodiment hasthe plurality of semiconductor lasers 8, 8 . . . disposed in a matrixwith m rows and n columns and irradiates the rectangular laserirradiation surface 12 with the plurality of semiconductor laser beamscorresponding to the disposed state. The entire region of therectangular laser irradiation surface 12 is irradiated with thesemiconductor laser beams having the substantially constant powerdensity collectively, so that a region which can be treated by a singlelaser irradiation can be enlarged substantially as compared with anexisting laser depilating apparatus having a plurality of semiconductorlasers disposed in a circular form. Besides, the depilating effect inthe enlarged laser irradiation region can be enhanced more uniformly.

[0066] Specific laser depilating treatment is performed by first shavinghair on a skin surface and applying cooling gel or the like to thetreatment region. In the laser depilating treatment process, thetreatment time is set to, for example, 5 to 60 minutes, and thesemiconductor laser beams are repeatedly irradiated and suspended withinthe treatment time. The semiconductor laser beams are irradiated whilegradually moving their positions on the skin surface. The irradiationtime of the semiconductor laser beams is determined as a lighting timeper irradiation as described above. While the irradiation of thesemiconductor laser beams is being suspended, cooling air is blown fromthe air nozzles 13 to the skin surface to retard the temperatureincrease of the skin. Thus, the depilating treatment is performed.

[0067] The laser depilating apparatus of this embodiment was used toactually perform the laser depilating treatment to find that a favorabledepilating effect could be obtained by irradiating the lasers under theabove-described conditions. Specifically, the laser depilating treatmentwas performed by irradiating a leg of a subject with the semiconductorlaser beams (800 nm as median) with the irradiation time T set to 3 secper irradiation while controlling the semiconductor laser beams to havean energy density in a range of 0.1 to 0.4 J/mm² at the time of theirradiation. The laser depilating treatment was performed for eightweeks. The laser treatment was performed two times a week for the firstfour weeks and one time a week for the next four weeks. It was confirmedas a result that plural subjects had favorable depilating effects(reduction in number of hair, reduction in hair shaft diameter (thinhair), decrease of pigment in hair, etc.).

[0068] Meanwhile, as a comparative example of the present invention, theirradiation time T of the semiconductor laser beams was lowered to 40msec per irradiation with the same power of the semiconductor lasers toperform the same treatment for eight weeks as the above-describedembodiment to find that favorable depilating effects could not beobtained. Besides, when the irradiation time T of the semiconductorlaser beams was set to 40 msec per irradiation and the irradiationenergy density was controlled to a range of 0.1 to 0.4 J/mm², thefavorable depilating effects could not be obtained either.

[0069] As described above, it is possible to obtain the laser depilatingeffects more securely and efficiently by utilizing the features of thesemiconductor laser beams that the absorption efficiency by melanin inhair shafts and germinative cells is high by the laser depilatingapparatus and the laser depilating treatment using it of thisembodiment. In the above-described embodiment, the use of the pluralityof semiconductor lasers was described, but the invention is not limitedto it and can also be applied to a laser depilating apparatus using asingle semiconductor laser.

[0070] In addition, all the plurality of semiconductor lasers 8, 8 . . .are not required to come on during the treatment, and only desiredsemiconductor lasers may be lit depending on a treatment area, a shapeof treatment region and the like. FIG. 9 is a block view showing astructure of the laser drive control section according to anotherembodiment of the invention. The laser depilating apparatus of thisembodiment sends a drive time signal for the semiconductor laser 8 fromthe control section 101 to the laser drive circuit 105 via a switchcircuit 106. A control signal is sent from the control section 101 tothe switch circuit 106 to turn on the switch of the semiconductor lasersso to light among the plurality of semiconductor lasers 8, 8 . . . .

[0071] Thus, the laser beams can be emitted from only desiredsemiconductor lasers among the plurality of semiconductor lasers 8, 8 .. . . Selection of desired semiconductor lasers enables to change alaser depilating treatment area. This configuration is effective inchanging a treatment area or a treatment portion by a single laserradiating probe 4.

Industrial Applicability

[0072] According to the laser depilating method and laser depilatingapparatus of the present invention, it becomes possible to obtain thedepilating effects more securely and efficiently by utilizing thefeature of the semiconductor laser beams that an absorption efficiencyby melanin in hair shafts and germinative cells is high. Such a laserdepilating method and laser depilating apparatus are effectively usedfor various kinds of depilating treatments. Besides, a treatment regioncan be increased by using a plurality of semiconductor lasers, and itbecomes possible to enhance a depilating treatment speed.

What is claimed is:
 1. A laser depilating method for depilatingtreatment by irradiating a skin surface with a laser beam emitted from asemiconductor laser, comprising: irradiating a treatment region of theskin surface with the laser beam for an irradiation time of 100 msec ormore per irradiation while controlling an energy density to a range of0.01 to 1 J/mm² when the skin surface is irradiated with the laser beam;and performing the depilating treatment by transmitting thermal energybased on the irradiation of the laser beam to the entire hair follicletissue of the treatment region.
 2. The laser depilating method accordingto claim 1, wherein the laser beam has a wavelength in a range of 750 to900 nm.
 3. The laser depilating method according to claim 1, wherein thelaser beam has a power density in a range of 0.01 to 5 W/mm².
 4. Thelaser depilating method according to claim 1, wherein the laser beam isirradiated for an irradiation time of 100 msec or more and 10 sec orless per irradiation.
 5. The laser depilating method according to claim1, wherein the laser beam is irradiated for the irradiation time of 1sec or more and 5 sec or less per irradiation.
 6. The laser depilatingmethod according to claim 1, wherein the laser beam has the energydensity in the range of 0.1 to 0.4 J/mm².
 7. The laser depilating methodaccording to claim 1, wherein the semiconductor laser is used inmultiple numbers, and a plurality of laser beams emitted from theplurality of semiconductor lasers are collectively irradiated to thetreatment region of the skin surface.
 8. A laser depilating apparatus,comprising: a semiconductor laser for emitting a laser beam having awavelength in a range of 750 to 900 nm; a radiating head having a lightpath for guiding the laser beam and a laser irradiation surface so toirradiate a skin surface subject to depilating treatment with the laserbeam emitted from the semiconductor laser; and an irradiation conditioncontrol section for controlling an energy density to a range of 0.01 to1 J/mm² when the skin surface is irradiated with the laser beam whilekeeping the irradiation time of the laser beam at 100 msec or more perirradiation.
 9. The laser depilating apparatus according to claim 8,wherein the irradiation condition control section controls at least oneselected from the irradiation time and a power density of the laser beamto make the laser beam having the energy density in the range of 0.01 to1 J/mm².
 10. The laser depilating apparatus according to claim 9,wherein the irradiation condition control section controls theirradiation time of the laser beam to the rang of 100 msec or more and10 sec or less per irradiation.
 11. The laser depilating apparatusaccording to claim 9, wherein the irradiation condition control sectioncontrols the power density of the laser beam to the range of 0.01 to 5W/mm².
 12. The laser depilating apparatus according to claim 8, whereinthe laser beam has the wavelength in the range of 780 to 810 nm.
 13. Thelaser depilating apparatus according to claim 8, further comprising: thesemiconductor laser in plural numbers; and an optical system forgathering and forming a plurality of laser beams emitted from theplurality of semiconductor lasers so to have the entire region of thelaser irradiation surface of the radiating head substantially irradiatedwith the laser beams.
 14. The laser depilating apparatus according toclaim 13, wherein the radiating head has the laser irradiation surfacein a rectangular shape, and the plurality of semiconductor lasers aredisposed to respectively irradiate substantially different regions inthe rectangular laser irradiation surface with the plurality of laserbeams.
 15. The laser depilating apparatus according to claim 14, whereinthe plurality of semiconductor lasers are supported by a member having aspherical holding surface so to have substantially constant distancesfrom individual light emitting points to a light-gathering point in theradiating head.
 16. The laser depilating apparatus according to claim13, further comprising: a laser switching section for emitting the laserbeam from any semiconductor laser among the plurality of semiconductorlasers.